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S. Jabri H. Souissi A. Souissi A. Meftah V. Sallet A. Lusson P. Galtier M. Oueslati 《Journal of Raman spectroscopy : JRS》2015,46(2):251-255
Wurtzite ZnO thin films were prepared on sapphire substrate by metal organic chemical vapor deposition (MOCVD). Raman scattering studies on different crystallographic textures were performed in the backscattering geometry, and polarization effect is investigated in different configurations and . ZnO Raman modes are investigated in each texture. In the case of ZnO thin film deposed on r‐() sapphire plane and using backscattering geometry, new Raman line was observed at 390 cm−1 because this mode has not been noticed in this geometry. It is shown that the frequencies of the quasi‐phonon modes of the examined thin film are in good agreement with the theoretical values calculated within the framework of Loudon model. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
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The photoluminescence (PL) at low temperature of three delta-doped AlGaAs/GaAs heterostructures is investigated under continuous and pulsed excitations. The PL under continuous excitations allows the identification of the trapping centres and probes the carrier's transfer to the GaAs channel. The time-resolved photoluminescence (TRPL) inquires about carrier dynamics and gives radiative lifetimes of different levels. The DX level shows two time constants of the intensity decay relating the splitting of the valence band under impurity strains which reduce the crystal symmetry. The two time constants evolve with temperature and exhibit an increase near T=50 K. 相似文献
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We investigate the thermodynamic properties of some quantum statistical systems with a fractional Hamiltonian in D-dimensional space. We calculate the partition function of the system of N fractional quantum oscillators and the thermodynamic quantities associated with it. We consider the thermal and critical properties of both Bose and Fermi gases in the context of the fractional energy and described by a fractional derivative. 相似文献
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A. Meftah J.-F. Wyart N. Champion L. Tchang-Brillet 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,44(1):35-45
The emission spectrum of thulium produced by a vacuum spark source was observed in
the wavelength range from 700 to 2320 ? on the 10.7 m normal-incidence vacuum ultraviolet spectrograph
at the Paris-Meudon observatory. In the unknown spectrum of Tm IV, more than 760 lines have been identified for the first
time as transitions
between 157 levels of 4f115d, 33 levels of 4f116p, 9 levels of 4f116s and 10 levels of the 4f12 ground
configuration. A parametric interpretation of the levels has been carried out using the Cowan codes.
Configuration interaction effects are discussed, in particular with the core-excited configurations 5p54f13 and 5p54f125d.
Radial Slater parameters derived from 4f12 levels are larger than those pertaining to trivalent Tm ions
in compounds. A selection of 105 prominent lines is given. 相似文献
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Using the path integral formalism, the fine structure and dynamics effects are taken into account for the study of the spectral line broadening in plasmas. A compact expression of the dipolar autocorrelation function (DAF) for an emitter in the plasma is derived for Lyman alpha lines with fine structure. The expression of the DAF takes into account the dynamics effects, which are represented by the time autocorrelation function of the electric microfield. The spectral line for the Lyman‐alpha case has been obtained in a compact form and plotted in the quasi‐static approximation and compared to a line obtained by a simulation. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
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The thermal annealing behavior of the Y3Al5O12, CaF2 and LiF single crystals bombarded at Algiers with reactor neutrons has been monitored by optical absorption spectroscopy. The irradiation was performed at about 315 K. On heating samples after irradiation, the optical absorption bands decrease and disappear completely at 873 and 523 K in the case of Y3Al5O12 and CaF2, respectively. Activation energies of 1.2±0.02 and 0.9±0.2 eV are estimated for Y3Al5O12 and CaF2, respectively. On the other hand, the LiF crystal shows a complex annealing behavior. Here, the optical absorption spectrum presents different shapes after each annealing temperature. Four steps are distinguished and discussed on heating samples from 300 to 673 K. Above 673 K, the absorption drops by about 50%; it completely disappears at 773 K. 相似文献